Such a semiconductor component with charge compensation structure and an associated fabrication method is disclosed in DE 101 32 136 C1. The charge compensation structure of this semiconductor component has, in cross section, a plurality of complementarily conducting regions which are stacked one on top of another and produce, through an alternation of successive epitaxy steps with selective ion implantation, a plurality of delimited sources of a dopant for the complementary conduction type stacked one on top of another. Vertical and lateral diffusion of the sources results in the formation of contiguous charge compensation zones of the complementary conduction type in the drift path of the semiconductor component.
Such a charge compensation structure has the disadvantage that the defect sources have to be applied in areal fashion through corresponding ion implantation masks, and thus cannot be arbitrarily reduced in terms of their lateral extent from a production engineering standpoint. What is more, said lateral extent is also increased after the selective ion implantation by virtue of the subsequent diffusion. The semiconductor body material required for such a charge compensation structure is no longer available for the current path of the drift path. On account of the photolithographic implantation masks, the lateral limits of the cross section of the known charge compensation structure require minimum sizes in the micron range and tolerances significantly in the submicron range. A further disadvantage is that the fabrication of such charge compensation zones necessitates a plurality of epitaxy steps, alignment steps, photolithographic masking steps and ion implantation steps, and also finally at least one diffusion step, which leads to a cost-intensive production method for such semiconductor components.
An alternative lateral semiconductor component is disclosed in the patent specification DE 198 28 191 C1 in which a trench structure is introduced into the epitaxial layer of the drift path instead of diffused charge compensation zones. Charge compensation zones with a complementary conduction type are subsequently indiffused into the walls and into the bottom of the trench structure, in which case, as source material of the dopant for the complementary conduction type, the trench structure is either filled with a highly doped polysilicon, or a doping glass is applied into the trench structure on the sidewalls and the bottom. Although the width of the active compensation zone is reduced at least in the edge regions by means of this method, the volume of the trench structure is not available for the current path between the two electrodes of the semiconductor component, so that, in this case, too, a considerable proportion of the epitaxial area has to be sacrificed for introducing the charge compensation structure in the drift path.
The document U.S. Pat. No. 6,608,350 B2 furthermore discloses a high-voltage-resistant vertically conducting semiconductor component having a multiplicity of deep trenches or holes in a weakly doped drift path. In one exemplary embodiment, in this case, too, the trench structures are filled by a semiconducting polysilicon body, but the complementarily conducting wall doping is no longer arranged in the bottom region of the trench structure, so that the polycrystalline, semiconducting silicon in the bottom region is in contact with the material of the drift path. Consequently, the polycrystalline silicon supplies a high-resistance current path between the two electrodes, thereby intensifying the influencing of the field distribution in the drift zones which proceeds from the charge compensation zones of the complementarily conducting walls of the trench structure. This solution nevertheless constitutes a disadvantage for the semiconductor components because the volume of the trench structure again makes no contribution to the current path of the drift zones.
Finally, the document U.S. Pat. No. 6,495,294 B1 discloses a method for fabricating a semiconductor substrate having an epitaxial film in a trench structure. For this purpose, a first epitaxial layer of a first conduction type is applied on a monocrystalline semiconductor wafer and a trench structure is etched into the epitaxial layer. In two stages, the trench structure is then filled with semiconducting monocrystalline material of a complementary conduction type with respect to the first conduction type to form charge compensation zones. In a first stage, an amorphous noncrystalline complementarily doped layer is deposited in the trench structure, which is subsequently subjected to heat treatment to form a monocrystalline complementarily doped seed layer. Afterward, in a second stage, a complementarily doped monocrystalline filling of the trench structure is grown on the monocrystalline seed layer. With this monocrystalline filling of the trench structure, a compensation zone that is defined exactly in terms of its width is available, which compensation zone occupies a considerable proportion of a drift path of a semiconductor component and thus disadvantageously constricts and reduces the epitaxial material of the first conduction type for the formation of current paths in drift zones. The semiconductor components mentioned above can be power semiconductor components.